Coolant leak. Root cause??
04-11-2020, 04:41 PM
#46
Rennlist Member
Thread Starter
The Devcon material is a professional grade repair compound similar to the stuff we used on damaged pump casings- an epoxy called Belzona- truly excellent stuff. The JB weld gets good reviews but have no access to it over here but use similar quality products from the likes of Bison.
The problem you are facing is knowing what the extent of the damage is and thus how far to take any attempted repair. That there is a leak path is one thing but it is quite possible [more likely highly probable] that the crack line is not passing coolant along its entirety. If I were to attempt a repair using epoxy it may be prudent to open up the crack line a bit using a dremel bit and then scour the surface of the Vee for at least half and inch either side of the crack line. Degreasing thoroughly is essential as is ensuring the surfaces the stuff is applied to are not wetted so the coolant needs to be drained. I would use a hot air gun to help dry the surfaces out and carb cleaner to degrease them. As to how much to use I would be looking to apply a layer about 6mm thick. Allow plenty of distance from where you think the crack ends. If it still weeps after that you can always rework it- nothing lost and everything to gain but do not be too surprised if it does not work . Just remember once you go down this path silver soldering and welding options are probably off the table later on.
The problem you are facing is knowing what the extent of the damage is and thus how far to take any attempted repair. That there is a leak path is one thing but it is quite possible [more likely highly probable] that the crack line is not passing coolant along its entirety. If I were to attempt a repair using epoxy it may be prudent to open up the crack line a bit using a dremel bit and then scour the surface of the Vee for at least half and inch either side of the crack line. Degreasing thoroughly is essential as is ensuring the surfaces the stuff is applied to are not wetted so the coolant needs to be drained. I would use a hot air gun to help dry the surfaces out and carb cleaner to degrease them. As to how much to use I would be looking to apply a layer about 6mm thick. Allow plenty of distance from where you think the crack ends. If it still weeps after that you can always rework it- nothing lost and everything to gain but do not be too surprised if it does not work . Just remember once you go down this path silver soldering and welding options are probably off the table later on.
I will also cover the crack with JB weld over a larger area.
But most important : clean and roughen the surface. Perhaps trying to back out any coolant fluid further into the coolant chamber via
air compressor so that all dirt is gone.
This together with heating the area so that the crack opens a bit so that JB weld enters fully into the crack
04-11-2020, 05:43 PM
#47
Rennlist Member
Hi Fred, I totally agree with your approach👌
I will also cover the crack with JB weld over a larger area.
But most important : clean and roughen the surface. Perhaps trying to back out any coolant fluid further into the coolant chamber via
air compressor so that all dirt is gone.
This together with heating the area so that the crack opens a bit so that JB weld enters fully into the crack
I will also cover the crack with JB weld over a larger area.
But most important : clean and roughen the surface. Perhaps trying to back out any coolant fluid further into the coolant chamber via
air compressor so that all dirt is gone.
This together with heating the area so that the crack opens a bit so that JB weld enters fully into the crack
It is not so much my recommended approach rather it is what I would do if I decided to go down that particular route. If the car is a keeper then the consequences are somewhat moot. Just remember that if you do decide to go down that route it pretty much makes the engine and by extension the car somewhat worthless on the used car market or so I would think if a potential future owner saw such.
If that was my motor at the very least I think I would try to fix it up using one of these modern self fluxing brazing rods in the first instance but I am struggling to remember the name of the material I have in mind- something like Durafix [?] as I recall. If all else fails then and only then would I try the epoxy route but I would try such before abandoning the engine completely.
I still recommend you try the dye pen route first as it will show a crack that you cannot see with the naked eye and thus hopefully give you some level of confidence that you know the extent of what you are dealing with and there are no guarantees of that.
"Chance favours the prepared mind"
04-11-2020, 07:08 PM
#48
Rennlist Member
Thread Starter
Hi Gerrit,
It is not so much my recommended approach rather it is what I would do if I decided to go down that particular route. If the car is a keeper then the consequences are somewhat moot. Just remember that if you do decide to go down that route it pretty much makes the engine and by extension the car somewhat worthless on the used car market or so I would think if a potential future owner saw such.
If that was my motor at the very least I think I would try to fix it up using one of these modern self fluxing brazing rods in the first instance but I am struggling to remember the name of the material I have in mind- something like Durafix [?] as I recall. If all else fails then and only then would I try the epoxy route but I would try such before abandoning the engine completely.
I still recommend you try the dye pen route first as it will show a crack that you cannot see with the naked eye and thus hopefully give you some level of confidence that you know the extent of what you are dealing with and there are no guarantees of that.
"Chance favours the prepared mind"
It is not so much my recommended approach rather it is what I would do if I decided to go down that particular route. If the car is a keeper then the consequences are somewhat moot. Just remember that if you do decide to go down that route it pretty much makes the engine and by extension the car somewhat worthless on the used car market or so I would think if a potential future owner saw such.
If that was my motor at the very least I think I would try to fix it up using one of these modern self fluxing brazing rods in the first instance but I am struggling to remember the name of the material I have in mind- something like Durafix [?] as I recall. If all else fails then and only then would I try the epoxy route but I would try such before abandoning the engine completely.
I still recommend you try the dye pen route first as it will show a crack that you cannot see with the naked eye and thus hopefully give you some level of confidence that you know the extent of what you are dealing with and there are no guarantees of that.
"Chance favours the prepared mind"
As this car is a keepers, I don't really mind that it is fixed this way.
But ofcourse, since I am rather a perfectionist, it is really bothering me that the engine not 100% reliable , even when patched.
So I have another engine in my sight, it is only the main block (without any heads, cams, etc..) : but is a M28.21 block of 1984 (euro L-jet block with 310 HP and electronic injection and other heads +cams)
My big question : will my heads, cams, pistons...fit this block ? My engine is M28.12
04-11-2020, 08:33 PM
#49
Fred’s advice about the dye check should be your first go to.
JB Weld is essentially a ‘glue’ product.
Rumors on the Internet say The Original dissolves in antifreeze, but they do manufacture a dedicated radiator product.
You seem very particular about your car, and perhaps almost old enough not to resort to this cheap product, just not all the way there. No offense, when I was 20 I bought a tube myself, for a different project and it failed, no surprise.
Fred’s advice about alternatives, more ‘professional’ routes, is what I would follow.
But if you must go the cheap route there are additives that promise to seal leaking radiators and blocks; yours might be an ideal candidate. Definitely a plus over smearing glue on the block.
JB Weld is essentially a ‘glue’ product.
Rumors on the Internet say The Original dissolves in antifreeze, but they do manufacture a dedicated radiator product.
You seem very particular about your car, and perhaps almost old enough not to resort to this cheap product, just not all the way there. No offense, when I was 20 I bought a tube myself, for a different project and it failed, no surprise.
Fred’s advice about alternatives, more ‘professional’ routes, is what I would follow.
But if you must go the cheap route there are additives that promise to seal leaking radiators and blocks; yours might be an ideal candidate. Definitely a plus over smearing glue on the block.
04-11-2020, 09:45 PM
#50
Rennlist Member
There is a Marine version of JB Weld. I used it on a threaded fuel tank insert.
04-12-2020, 03:36 AM
#51
Rennlist Member
Also good idea about the pen, this way I am sure I have covered the crack completely.
As this car is a keepers, I don't really mind that it is fixed this way.
But ofcourse, since I am rather a perfectionist, it is really bothering me that the engine not 100% reliable , even when patched.
So I have another engine in my sight, it is only the main block (without any heads, cams, etc..) : but is a M28.21 block of 1984 (euro L-jet block with 310 HP and electronic injection and other heads +cams)
My big question : will my heads, cams, pistons...fit this block ? My engine is M28.12
As this car is a keepers, I don't really mind that it is fixed this way.
But ofcourse, since I am rather a perfectionist, it is really bothering me that the engine not 100% reliable , even when patched.
So I have another engine in my sight, it is only the main block (without any heads, cams, etc..) : but is a M28.21 block of 1984 (euro L-jet block with 310 HP and electronic injection and other heads +cams)
My big question : will my heads, cams, pistons...fit this block ? My engine is M28.12
We still do not know what caused this failure but the location and nature of the failure do suggest a frost heave type failure. Simple statics suggest that primary failure occurred somewhere around the logical point of maximum overturning moment and damage to one localised position is most unlikely - that is about the most that can be said.
The "good thing" is that during normal operation pressurisation of the water jacket is not an essential requisite. The normal operating temperature of the coolant leaving the engine is about 95C whereas the boiling point of a 50:50 coolant mix is about 105C. Pressurisation raises this to about 110C so a bigger margin of safety. Pressurisation is caused by thermal expansion of the coolant leading to compression of the air space in the top of the expansion vessel so keeping the level in the expansion tank at the low end of the acceptable range or maybe a bit lower will help your situation assuming you succeed in sealing the system so that it can in fact pressurise. You do not live in the hottest part of the planet so optimal engine cooling is not really an issue for you- just make sure your ac condenser is clean and not crudded up. If your ac system is non functional just remove the condenser altogether but the 928 without operational ac is much less of a car in my opinion.
As to what will fit and what will not as I am aware most 16 valve engine parts are mechanically interchangeable but our resident experts will guide you on such as to what you can and cannot do should you go down the rebuild path.
Again investigate some of these modern brazing rods that require little in the way of skill to use. Localised heating of the block to get the stuff to flux should be possible- whether it is wise to attempt such in situ is a bit more debatable. At the very least I would drain the fuel system in the engine bay- presumably the fuel rails are off the engine by now anyway but you can discuss such mitigations as and when you decide what path of action to take.
04-12-2020, 07:25 AM
#52
Rennlist Member
Thread Starter
The problem with trying to seal a leak path like this is that you will never really know whether it is fixed permanently and thus the possibility that it will spring a leak in another adjacent location. If you can live with this possibility all well and good.
We still do not know what caused this failure but the location and nature of the failure do suggest a frost heave type failure. Simple statics suggest that primary failure occurred somewhere around the logical point of maximum overturning moment and damage to one localised position is most unlikely - that is about the most that can be said.
The "good thing" is that during normal operation pressurisation of the water jacket is not an essential requisite. The normal operating temperature of the coolant leaving the engine is about 95C whereas the boiling point of a 50:50 coolant mix is about 105C. Pressurisation raises this to about 110C so a bigger margin of safety. Pressurisation is caused by thermal expansion of the coolant leading to compression of the air space in the top of the expansion vessel so keeping the level in the expansion tank at the low end of the acceptable range or maybe a bit lower will help your situation assuming you succeed in sealing the system so that it can in fact pressurise. You do not live in the hottest part of the planet so optimal engine cooling is not really an issue for you- just make sure your ac condenser is clean and not crudded up. If your ac system is non functional just remove the condenser altogether but the 928 without operational ac is much less of a car in my opinion.
As to what will fit and what will not as I am aware most 16 valve engine parts are mechanically interchangeable but our resident experts will guide you on such as to what you can and cannot do should you go down the rebuild path.
Again investigate some of these modern brazing rods that require little in the way of skill to use. Localised heating of the block to get the stuff to flux should be possible- whether it is wise to attempt such in situ is a bit more debatable. At the very least I would drain the fuel system in the engine bay- presumably the fuel rails are off the engine by now anyway but you can discuss such mitigations as and when you decide what path of action to take.
We still do not know what caused this failure but the location and nature of the failure do suggest a frost heave type failure. Simple statics suggest that primary failure occurred somewhere around the logical point of maximum overturning moment and damage to one localised position is most unlikely - that is about the most that can be said.
The "good thing" is that during normal operation pressurisation of the water jacket is not an essential requisite. The normal operating temperature of the coolant leaving the engine is about 95C whereas the boiling point of a 50:50 coolant mix is about 105C. Pressurisation raises this to about 110C so a bigger margin of safety. Pressurisation is caused by thermal expansion of the coolant leading to compression of the air space in the top of the expansion vessel so keeping the level in the expansion tank at the low end of the acceptable range or maybe a bit lower will help your situation assuming you succeed in sealing the system so that it can in fact pressurise. You do not live in the hottest part of the planet so optimal engine cooling is not really an issue for you- just make sure your ac condenser is clean and not crudded up. If your ac system is non functional just remove the condenser altogether but the 928 without operational ac is much less of a car in my opinion.
As to what will fit and what will not as I am aware most 16 valve engine parts are mechanically interchangeable but our resident experts will guide you on such as to what you can and cannot do should you go down the rebuild path.
Again investigate some of these modern brazing rods that require little in the way of skill to use. Localised heating of the block to get the stuff to flux should be possible- whether it is wise to attempt such in situ is a bit more debatable. At the very least I would drain the fuel system in the engine bay- presumably the fuel rails are off the engine by now anyway but you can discuss such mitigations as and when you decide what path of action to take.
my car currently runs without AC since
Po removed it since it was broken but
I was into repairing it for the coming months ...unfortunately the crack thought otherwise😬
Fuel lines are removed with the complete kjet air/mixture box.
The throttle house together with inlet
tubes and injectors are also removed
as one piece.
So the path is cleared for my intervention with JB weld.
Luckily here in Belgium we do not have
hot climats although during last 3 years
summers are becoming more hot than
before. But one can see an average
temperature of about 18 till 20 degrees Celsius
As for fitting another engine , I will stick
to the 4.7l kjet or lh jet. This way i can reuse my kjet components. I am more an oldschool guy😀
04-12-2020, 07:49 AM
#53
Rennlist Member
I suspect that your problem is a somewhat rare occurrence if not unique and quite possible that our most experienced practitioners have not come across such a failure - this makes your case rather interesting.
04-12-2020, 10:11 AM
#54
Rennlist Member
Thread Starter
I am also waiting for feedback of a friend of mine that is a professional photo-laser welder.
04-12-2020, 10:38 AM
#55
Rennlist Member
The more Fred talks about it, the more convinced I am that, if you're going to try a repair, brazing is probably the best, first thing to try. I'll be honest, apart from the general temperature requirements and maybe some of the material components, it's not clear to me what the differences are between brazing and soldering. Having explored a bit of the solder world for work, there are products available that work at a temperature much higher than what this part of the engine will see and which might be appropriate. A colleague of mine is a metallurgist and has talked to me about aerospace solders, which I am told are significantly different than what is available commonly and might be the ticket to what you need. The conditions that part of the block sees, as described by others above, don't sound particularly extreme and there is likely a metal based repair path readily available.
I'll keep reading this thread to see what you come up with. The laser welding sounds totally cool.
Wishing you the best
I'll keep reading this thread to see what you come up with. The laser welding sounds totally cool.
Wishing you the best
04-12-2020, 11:18 AM
#56
Team Owner
If your gonna go with the Epoxy fix I would suggest that you use this stuff instead of the JB.
Its Called Belzona 1111 its sounds like what you would need to fix this
CAT recommends it for fixing damaged engine blocks and the online reviews seem to say that its the best stuff
NOTE check E bay and online for purchase options
Watch you tube videos on how to use this epoxy,
this might be the best epoxy choice for your block
Its Called Belzona 1111 its sounds like what you would need to fix this
CAT recommends it for fixing damaged engine blocks and the online reviews seem to say that its the best stuff
NOTE check E bay and online for purchase options
Watch you tube videos on how to use this epoxy,
this might be the best epoxy choice for your block
04-12-2020, 11:42 AM
#57
Rennlist Member
The more Fred talks about it, the more convinced I am that, if you're going to try a repair, brazing is probably the best, first thing to try. I'll be honest, apart from the general temperature requirements and maybe some of the material components, it's not clear to me what the differences are between brazing and soldering. Having explored a bit of the solder world for work, there are products available that work at a temperature much higher than what this part of the engine will see and which might be appropriate. A colleague of mine is a metallurgist and has talked to me about aerospace solders, which I am told are significantly different than what is available commonly and might be the ticket to what you need. The conditions that part of the block sees, as described by others above, don't sound particularly extreme and there is likely a metal based repair path readily available.
I'll keep reading this thread to see what you come up with. The laser welding sounds totally cool.
Wishing you the best
I'll keep reading this thread to see what you come up with. The laser welding sounds totally cool.
Wishing you the best
Commerical tin/lead solder forms a eutectic that melts at something like 180C- a relatively low temperature application thus why it is easy and popular to use. Brazing [also called silver soldering] is a step up the ladder using materials that melt at around 430C or so. Aluminium melts at around 660C but some modern proprietary alloys the like of which I mentioned earlier can melt at much lower temperatures thus making them easier to work with whilst providing impressive strength properties in the resulting repair.
Welding by definition requires melt of the parent metal.
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Zirconocene (04-12-2020)
04-12-2020, 12:00 PM
#58
Rennlist Member
Thread Starter
If your gonna go with the Epoxy fix I would suggest that you use this stuff instead of the JB.
Its Called Belzona 1111 its sounds like what you would need to fix this
CAT recommends it for fixing damaged engine blocks and the online reviews seem to say that its the best stuff
NOTE check E bay and online for purchase options
Watch you tube videos on how to use this epoxy,
this might be the best epoxy choice for your block
Its Called Belzona 1111 its sounds like what you would need to fix this
CAT recommends it for fixing damaged engine blocks and the online reviews seem to say that its the best stuff
NOTE check E bay and online for purchase options
Watch you tube videos on how to use this epoxy,
this might be the best epoxy choice for your block
But so is the price : almost 10x price of JB weld....
Here are my options , ranked as to the costs of repair/renew :
1. JB Weld ($ 24)
2. Belzona ($210 )
3. Welding ($ 400)
4. other engine ( $ 2500)
The future seems alot brighter for my engine than 2 days ago , thanks to you all, guys :-)
04-12-2020, 01:33 PM
#59
Team Owner
The Belonza has silicon mixed into it ,
so it sounds like it would be a better match for the silicon block,
I know its not JB weld cost , BUT look around I found some on E bay that was 15% used for 45.00 in USA.
so it sounds like it would be a better match for the silicon block,
I know its not JB weld cost , BUT look around I found some on E bay that was 15% used for 45.00 in USA.
04-12-2020, 06:42 PM
#60
Advanced
I would stick with the JB Weld. If your worried about the appearance for resale purposes I would suggest cutting a piece of 3mm aluminium plate about 25mm wide and a bit longer than the crack. Round off the corners and the top edge. Scribe around the edge after you abraid and clean both surfaces. Apply about 2 or 3mm of JB weld all over inside the scribed area and push down the patch just enough so so glue oozes out the sides. Apply hot air over the patch until the glue showing goes glossy. Once you put that Kjet stuff back in you won't see the area too well but in 20 years or so check on your handiwork. The area could be tig welded or splatter welded with mig, the block accepts weld easily. Don't bother with any of the aluminium brazing rods you see advertised and don't consider silver soldering either on aluminium. Any naked flame welding on aluminium is difficult as there is no change in colour as the material gets hot so it's easy to blow holes! I have JB weld slopped on a poor aluminium weld I did on my Fiat race cars coolant system that is going to last forever.